Reference plane

Reference plane is a plane marked on the ISO headforms at a specified distance above and parallel to the basic plane (see Figure 3 of this part).

Source

16 CFR § 1203.4

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Scoping language

Basic plane means an anatomical plane that includes the auditory meatuses (the external ear openings) and the inferior orbital rims (the bottom edges of the eye sockets). The ISO headforms are marked with a plane corresponding to this basic plane (see Figures 1 and 2 of this part).

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